It is well known to utilize a pressure pulse in a well for measuring the liquid level of the well.
The present invention is directed to an improved gas gun for producing a pressure pulse in a well and measuring the pressure variations in the well which is an indication of the liquid level in the well. The improved gas gun may utilize a gas charge or may use the pressure of the well gas, if sufficient, to provide the pressure pulses for measurement. In addition, the gas gun of the present invention may be remotely operated if desired.